Looks like he lost all control. Could it have been the Jesus nut?
no because the blades were still attached
That’s not necessarily loss of control, it could be he was just too busy trying to make it a survivable crash that he could not spare the time/energy to talk to ATC. First priority is flying, communicating is second.
I’m not sure how everything is connected, would a transmission failure take out the tail rotor too?
I notice the helicopter starts turning to the left as it starts to fall. The Jet Ranger’s tail rotor pushes in that direction naturally. Tail rotor failure would cause a right turn. Main rotor failure would cause a left turn. I guess with a sudden loss of both rotors, the main rotor torque would instantly drop to zero and the freewheeling tail rotor might continue to do it’s job (turn the nose left) for a moment.
Of course, maybe the left turn doesn’t mean anything. The pilot might have pushed left pedal during an unrelated failure. I’m just curious if the left turn tells us anything. I think it may tell us that tail rotor failure is unlikely unless accompanied by main rotor failure.
The main transmission transfers the power from the engine to the rotor system. Should there be a main transmission failure, the rotor system should remain intact. Of course you could have a failure of the gearbox that joins the main and tail rotors, but if the engine/rotor system interface is what failed you simply have an unpowered rotor system.
In American production helicopters the main rotor turns counter-clockwise, so torque makes the fuselage turn right. The anti-torque rotor (tail rotor) is adjusted by means of the pedals to provide a counteracting force. In case of an engine or transmission failure, torque is taken away – but the pilot still has the left pedal applied. (Note: Unlike airplanes, the pedals are not spring-loaded, so they stay where you put them.) A left yaw is natural and expected until the pilot applies right pedal to set the anti-torque rotor pitch such that it is no longer counteracting the torque that is no longer there.
Update. The helicopter had mechanical problems that required flight cancellations in day prior to the crash from the Honolulu Star Advertiser. I only have the print version (Luddite!!); teaser below. Nothing in the article details what the mechanical issue was.
Tour company cited ‘mechanical issue’ before copter crash
By Dan Nakaso
Posted on February 21, 2016 1:30 am
An “unforeseen mechanical issue” plagued an Oahu tour company’s Bell 206B helicopter in the days before it crashed into Pearl Harbor Thursday morning, according to an email that Genesis Helicopters sent to a customer.
Interesting read, this thread. But one thing has bothered me from the very beginning of it. The very first word, in fact.
Do rotary-winged aircraft enthusiasts self identify as “rotorheads”? I suppose it makes sense. I just have never heard it.
Well I’ve been called worse.
Update: The 16 yr old died today. He did not get out of the helicopter immediately. He was in critical condition since the accident. The family donated his organs. Two other passengers are still hospitalized in stable condition. Two others and the pilot were treated and released.
A multipurpose word, I guess:
I agree with Machine Elf. Though ‘rotorhead’ might be considered derogatory when used by fixed-wing pilots, I think it’s really just good-natured ribbing. Many helicopter pilots do refer to themselves as ‘rotorheads’. As for the hub, I would use two words: ‘rotor head’. (Actually, I usually call it the hub.)
Fixed-wing pilots like to say that helicopters don’t fly; they’re so ugly the Earth repels them. Or they say they’re 10,000 parts trying to fly in different directions and kill the pilot. Or they say that helicopters don’t fly; they beat the air into submission. But two former-military helicopter pilots I used to work for said that unless you can fly a helicopter, your pilots wings should only have one wing on them. And of course, runways are for fashion models. 
Update: The pilot testified yesterday that he felt a vibration first, then felt/heard a grinding noise, then a bang. Engine rpm was fine but rotor speed dropped. He was attempting to auto-rotate to a field landing but a crowd of tourists were in the way so he ditched in the water.
Description would match a transmission failure.
“Jesus nut”? A nut that when removed every piece of metal comes apart and falls to the ground a la cartoons?
Also, I think I’m getting that “chip detector” is not necessarily a detector that is embodied in a microchip–which I first thought–but something which detects literal chips of metal flying around?
Jesus nut, or Jesus pin, is the pin and nut that hold the main rotor to a helicopter’s mast. You pray to Jesus it doesn’t fail.
Chip detector are magnetic plugs in the transmissions, past which oil circulates. If a transmission begins to fail, metal particles will circulate with the oil. These particles, or ‘chips’, are attracted by the magnetic plug where they complete a circuit and illuminate the chip detector annunciator on the panel.
Helicopter:
- 500 aerodynamic errors cancelling each other out
- 15,000 parts flying in close formation
Even though the pilots crashing into the water cost one guy’s life…IMO if he had hit land at that vertical speed EVERYBODY on board would have probably died…and probably a bystander or two in addition from flying parts.
After examination during preflight, I always think ‘Best not to think about it.’ 
There’s single points of failure in every aircraft. Helos just have more of them and they tend to be moving parts rather than static structure.
Here’s an example of a fixed-wing single failure point in action: C130A fire bomber loses wings.wmv - YouTube
The big difference is helo drivers & mechanics have a chance to look at their jesus nut before each flight. The corresponding points in an airplane are maybe not inspected even once between being built in the factory & their eventual endpoint: inflight failure or being chopped up for scrap in a boneyard.